"Video is exploding across Facebook. ... What's happening with live on Facebook is really exciting. We're not yet focused on monetization," Sandberg said.

She added, "Marketers know that people are on mobile. The average American consumer is checking his or her smartphone 150 times a day. So if you need to reach people, you need to be where they are, and the best place to do that is Facebook and Instagram."

Previously, Sandberg was vice president of global online sales and operations at Google and chief of staff for the U.S. Treasury Department during the Clinton administration.